1. Field of the Invention
The present invention relates to an ultrasonic transmitting unit which extends along a longitudinal axis and which is configured to transmit an ultrasonic vibration from a proximal direction toward a distal direction.
2. Description of the Related Art
Ultrasonic transmitting units extending along a longitudinal axis are disclosed in the specification of Jpn. PCT National Publication No. 2010-535089 and the specification of Jpn. PCT National Publication No. 2000-506431. Each of the ultrasonic transmitting units includes a columnar portion and an ultrasonic probe connected to a distal direction side of the columnar portion. An ultrasonic generating portion such as an ultrasonic vibrator which is configured to generate an ultrasonic vibration is attached to the columnar portion. The ultrasonic vibration generated in the ultrasonic generating portion is transmitted from a proximal direction toward a distal direction through the columnar portion and the ultrasonic probe.
Furthermore, in each of the ultrasonic transmitting units, the columnar portion is provided with a sectional area changing portion (a horn portion) in which a sectional area perpendicular to the longitudinal axis changes. Due the sectional area changing portion, an amplitude of the ultrasonic vibration increases.